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A = ( 2 x + 4 ) ( 3 x - 1 ) - ( 2 x + 4 )²
1 ) A = 2 x * 3 x + 2 x * - 1 + 4 * 3 x + 4 *-1 - ( 4 x² + 16 x + 16 ) (identité)
= 6 x² - 2 x + 12 x - 4 - 4 x² - 16 x - 16
= 2 x² - 6 x - 20
2 ) A = ( 2 x + 4 ) ( 3 x - 1 - 2 x - 4 )
= ( 2 x + 4 ) ( x - 5 )
3 ) si x = 1
A = ( 2 + 4 ) ( 1 - 5 ) = 6 * - 4 = - 24
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